Heart tissues of CD-1 mice inoculated with coxsackievirus B3 (CVB3) are extracted for soluble antigens which induce immunoreactivity in sensitized peritoneal exudate cells taken from CVB3-immunized mice, as assessed by the agarose droplet cell-migration inhibition assay. Our data suggest that these antigens are not virion antigens. Several biochemical and biophysical techniques will be used to identify and characterize these antigens, including column chromatography with charged resins and polyacrylamide gel electrophoresis. Studies on the nature of the immunoreactive antigens will be conducted using enzymatic treatment prior to bioassay and using specific stains for polyacrylamide gels. Attempts will be made to develop radioimmunoassays for both the immunoreactive cardiac antigens and antibodies to these antigens. Mice inoculated with CVB3 will then be examined for production of antibodies against the immunoreactive cardiac antigens and against virion antigens. We will attempt to follow cell-mediated immune responses against the immunoreactive cardiac antigens by development of a lymphocyte blast transformation assay. This latter technique will also be used to study the mechanism by which neonate CD-1 mice which survive inoculation with amyocarditic temperature-sensitive mutants of CVB3 become resistant to induction of myocarditis following inoculation of parent wild type (myocarditis) virus during adolescence.